Q: Is Roof Algae the same as Driveway mold?

Two years ago I hired a local company to “roof shampoo” the black algae stains off my roof. Unfortunately, it was very costly, and stains are beginning to reappear. In the meantime, my driveway, retaining wall, and back patio are showing black marks. I don’t know if those marks are caused by the same algae or if they are mold. I want to order products from you to do the cleaning myself, but am not sure which products to order.

Is it possible for you to tell me if the concrete stains are caused by the same algae as was on my roof, or do you think it is caused by mold?

Diana from Pennsylvania

A: Hard to say for sure, but black Algae and mold are cleaned the same way.

Diana, it is pretty common for the terms mold, mildew and algae to be used interchangeably. For now we’ll just refer to them as “black stains”.

You mentioned that 2 years ago a roof shampoo company removed black roof stains, and now those roof stains are returning. It’s not surprising because the mold, algae and mildew that form the stains typically will grow back 15-24 months after being removed. The spores that cause these stains are airborne, and probably landed back on the roof a few weeks after cleaning, and have been growing ever since.. We recommend for Roof Stain Prevention using Roof Armor every year to wipe out any mold colonies that have been growing. Roof Armor is only applied to a visibly clean roof.

Second the black stains on your retaining wall and concrete are most likely caused by the same mold or algae. Either way the same product can be used to clean them both. Cleaner Today OX products can be used on Siding, Wood, Concrete, Patios and Retaining Walls. Choose from Roof OX, Siding OX or Wood Ox.